Replace error-prone `create_random_data` with a reliable implementation

`create_random_data` is an error-prone function that returns a pointer to allocated memory using malloc.

As mentioned in #2177:
> we really ought to remove use of the create_random_data function entirely given that it's so error-prone. This shouldn't be too bad, since there are only a dozen or so places where create_random_data is called, and about half of the uses are in these two files.

Start by locating every call to `create_random_data` and read the related discussion in #2177, paying attention to the two files identified there. Replace or remove the function's uses across the reported call sites, with completion meaning no remaining use of `create_random_data` and the OpenCL CTS tests still passing.

Written by the indexing model from the issue text.